Presentation on theme: "Aim: Recognise that current will not flow around an incomplete circuit. Identify a range of materials that allow a current of electricity to flow around."— Presentation transcript:
Aim: Recognise that current will not flow around an incomplete circuit. Identify a range of materials that allow a current of electricity to flow around a circuit.
Complete and incomplete circuits 1. Build the circuit shown above. What happens to the bulb when the circuit is complete? 2. Starting from the positive side of the cell, trace with your finger the path followed by the electricity as it flows around the circuit. 3. Now remove one of the wires to the left of the bulb. What happens to the bulb? 4. Again, starting from the positive side of the cell, try to trace the path the electricity should follow around the circuit. 5. Reconnect this wire and disconnect a wire which is to the right of the bulb. What happens? 6. Repeat instruction 4.
Questions 1. What is a complete circuit? 2. What is an incomplete circuit? 3. What happens to the bulb when the circuit is complete? Explain why this happens. 4. What happens to the bulb when the circuit is incomplete? Explain why this happens.
Conductors and Insulators. Build the circuit above. Place a variety of materials between the crocodile clips to test them. Record your results in a table.
Conductors and Insulators Name of MaterialConductor or Insulator?
Copy and Complete Electricity is a flow of _____________ (negatively charged particles). Electricity can flow through____________ but not through _____________. ________ are good conductors of electricity. Electrons Conductors Insulators Metals
Aim: Show how to represent circuit components as symbols. Explain the role of cells and switches in circuits. Describe and understand the effect of adding cells in circuits
Batteries and Switches Questions: Q1. What happened to the brightness of the bulb when you add more batteries? Explain why Q2. What happens to the bulb in circuit D? Explain why.
Aim: Use an ammeter to measure current in a circuit Describe the effect on current of adding more components in a circuit. Explain how a fuse works
The flow of current Current in a circuit is ____ used up. Current which leaves a cell returns to it. Current leaves from the ________ terminal and returns to the negative terminal. The cell is a device which gives ________to components of the circuit. ___________ is what makes the current flow. A battery with a 9v rating will make the same lamp _________ than one with a 4.5v rating. not positive energy Voltage brighter
Which fuse? Very thin copper wire has a greater resistance than thicker copper wire. The thicker the wire the lower the resistance. Complete the sentences: breaks melts protects If the current flow is too high then the wire in the fuse …… and ……….. The circuit. This ……… the device so that components themselves do not melt. Fuse 5 amp13 amp Wire is…thicker / thinner Resistance is…higher / lower Used in…kettle / ipod
Which fuse? Very thin copper wire has a greater resistance than thicker copper wire. The thicker the wire the lower the resistance. If the current flow is too high then the wire in the fuse melts and breaks the circuit. This protects the device so that components themselves do not melt. Fuse 5 amp13 amp Wire is…thinnerthicker Resistance is…higherlower Used in…ipodkettle
Aim: Explain the features of series and parallel circuits. Build a complete parallel and series circuit
Parallel circuits Current in a parallel circuit is ______ used up. However it may not be the same everywhere you measure it. The current ________ when it comes to a branch. The ______ in the branches _______ up to the current ______ and returning to the ____________. current not splits up leaving battery adds
Aim: Use analogies to explain how electrical circuits work Create your own analogy to explain how circuits work.
What is the missing current reading? A1A1 A2A2 A3A3 A4A4 1 2 3 4 A1 = 4 amps A2 = 3 amps A3 = A4 = Credits! 1 amp 4 amps
A circuit is like a central heating system in a house: Boiler and pump radiator High pressure low pressure There is a pump that pushes water round the system. The water everywhere starts to move AT THE SAME TIME There are pipes that CARRY the water. In the pipes the water is FLOWING. Flow of water
An electrical circuit is very similar to a central heating system. The bulb in the circuit is like a radiator. An electrical device uses electrical energy supplied by the circuit. battery lamp wires Instead of a flow of water, electricity flows in an electrical circuit. The wires are like pipes; they carry the electricity round the circuit. This is called the electrical current. The electrical current is pushed by the battery, which has the same function as the pump and boiler. The strength of push provided by the battery is called its voltage.
Homework Research and find out what discoveries the following scientists made about electricity. Thomas Edison Luigi Galvani Alessandro Volta André-Marie Ampère Write in your own words what their discovery was and find a picture of the person to illustrate. (1 page in your book)
Aim: Describe what produces resistance in a circuit Explain what effect resistance has on current.